For millennia, people have written secret messages in invisible ink, which could only be read under certain lights or after developing with certain chemicals. Now, scientists have come up with a way of encoding messages in the colours of glowing bacteria.

The technique, dubbed steganography by printed arrays of microbes (SPAM), creates messages that can be sent through the post, unlocked with antibiotics and deciphered using simple equipment. It is described in the Proceedings of the National Academy of Sciences [1].

For years, scientists have been able to encode messages in biological molecules such as DNA or proteins. Biologist Craig Venter wrote his name, along with several quotations, into the DNA of the partially synthetic bacteria that he unveiled last year [2].

Last night, in response to a worldwide surge in interest, the OPERA experiment released a paper that describes the experiments that appear to show neutrinos traveling faster than the speed of light. And today, CERN broadcast a live seminar in which one of the work’s authors described the content of the paper. Both of those emphasized the point of our initial coverage: figuring out whether anything is traveling beyond the speed of light requires incredibly accurate measurements of time and distance, and the OPERA team has made an extensive effort to make its work as accurate as possible.

As a spokesperson for the MINOS neutrino experiment told Ars yesterday, there are three potential sources of error in the timing measurements: distance errors, time-of-flight errors, and errors in the timing of neutrino production. The vast majority of both the paper and the lecture were dedicated to discussing how these errors were reduced (the actual detection of the neutrinos was only a small portion of the paper).

A sophisticated new camera system can detect lies just by watching our faces as we talk, experts say. The computerised system uses a simple video camera, a high-resolution thermal imaging sensor and a suite of algorithms.

Researchers say the system could be a powerful aid to security services. It successfully discriminates between truth and lies in about two-thirds of cases, said lead researcher Professor Hassan Ugail from Bradford University.

If it’s true, it will mark the biggest discovery in physics in the past half-century: Elusive, nearly massless subatomic particles called neutrinos appear to travel just faster than light, a team of physicists in Europe reports. If so, the observation would wreck Einstein’s theory of special relativity, which demands that nothing can travel faster than light.

In fact, the result would be so revolutionary that it’s sure to be met with skepticism all over the world. “I suspect that the bulk of the scientific community will not take this as a definitive result unless it can be reproduced by at least one and preferably several experiments,” says V. Alan Kostelecky, a theorist at Indiana University, Bloomington. He adds, however, “I’d be delighted if it were true.”

The data come from a 1,300-metric-ton particle detector named Oscillation Project with Emulsion-tRacking Apparatus (OPERA). Lurking in Italy’s subterranean Gran Sasso National Laboratory, OPERA detects neutrinos that are fired through the Earth from the European particle physics laboratory, CERN, near Geneva, Switzerland. As the particles hardly interact at all with other matter, they stream right through the ground, with only a very few striking the material in the detector and making a noticeable shower of particles.

Most of the renewable energy sources that are under consideration involve an obvious source of energy — light, heat, or motion. But this is the second time this year there has been a paper that has focused on a less obvious source: the potential difference between fresh river water and the salty oceans it flows into. But this paper doesn’t simply use the difference to produce some electricity; instead, it adds bacteria to the process and takes out a portable fuel: hydrogen.

The process is still fundamentally electrochemical. Sea water and fresh water are placed on opposite sides of a membrane that allows ions through, but prevents the passage of water molecules. The ions will move to the fresh water to balance osmotic forces, which will create a charge difference that can be harvested for various purposes. The voltage produced in a single one of these cells is small, but the source of the power is essentially unlimited and is available 24 hours a day.

Earlier this year, graduate students suddenly found themselves deprived of a major source of procrastination when updates of the Piled Higher and Deeper Comics suddenly reduced to trickles. The hiatus led to a widespread speculation that Jorge Cham, the creator of the comics, fell victim to (*gasp*) procrastinitis after advocating for the habit over many years through his worldwide speech tour titled “the Power of Procrastination.”

A team of researchers from universities across America are rooting through millions of molecules to hunt down a material that can create efficient and cost-effective solar cells — and they need your computer power to do it.

Currently, the cost of electricity from silicon solar cells is about ten times that of other energy sources. So to put solar on level pegging researchers are hunting down organic materials that have a conducting efficiency of 10 to 15 percent and an average lifetime of more than a decade.

Organic cells also have the ability to be molded into different shapes, they can be made semi-transparent and are much lighter than inorganic materials. They’re cheaper and easier to produce, too, and are non-hazardous.

CHANDLER, Ariz. — Amy Furman, a seventh-grade English teacher here, roams among 31 students sitting at their desks or in clumps on the floor. They’re studying Shakespeare’s “As You Like It” — but not in any traditional way.

At the start of the school year, Amy Furman tries to inspire her students at Aprende Middle School to write. “I start with pens and pencils,” she says, but computers help the students edit their thoughts and work.

In this technology-centric classroom, students are bent over laptops, some blogging or building Facebook pages from the perspective of Shakespeare’s characters. One student compiles a song list from the Internet, picking a tune by the rapper Kanye West to express the emotions of Shakespeare’s lovelorn Silvius.

It is another escalation in the computer security arms race. Software that can uncover all of a person’s online activity could, in the hands of the police, put more sex offenders behind bars – but it may also be exploited to develop new ways of avoiding being caught.

Researchers from Stanford University in California have managed to bypass the encryption on a PC’s hard drive to find out what websites a user has visited and whether they have any data stored in the cloud.

It is easy enough to make software do what you want it to. You could tell your email client to recognise and immediately delete any unwanted messages – say, any from your mother-in-law that contain the word “visit”, but not the word “cake”. Now, Zhen Xie from Harvard University and MIT has found a way of filtering undesirable human cells – in this case, a specific type of cancer cell – with similar ease.

Xie has developed a genetic “logic circuit” that prompts cells to kill themselves if the levels of five molecules match those of a cancer cell. Yaakov Benenson, who led the study, says, “In the long term, the circuits’ role is to act like miniature surgeons that can identify and destroy cancer cells.” That is a very long way off, but the study is a promising step in the right direction.